I would say direct because the more gallons of gasoline used, the bigger the cost.
Answer: 12a.) slope is 125, y-intercept is 50 (started at 50 ft)
12b.) f(3) = 425 feet
12c.) 3.6 hours
Step-by-step explanation:
12a.) The slope equation is y = mx+b, where m is the slope, and b is the y intercept.
12b.) to find f(3) you could either plug it into the equation given (125x+50) or pretend there is a vertical line at 3 on the x axis, and where it crosses the line given would be the answer.
12c.) He is climbing a 500 ft cliff, and according to the graph, it takes him 3.6 hours to do it. Another way to find this answer would be to find f(3.6), which is indeed 500 ft.
Hope this helps!
Easiest ways to solve them are to take the denominator and numerator and and divide the one you are asked to use to answer and divide and see if it works on both.
Example: first 105 / 15 = 7 ) Then: 105 / 7 = 15
119 ) 119 / 7 = 17
Hope I helped. :D